The problem is _____ difficult for me _____ solve.

—Thank god, you finally returned home ________. —You can never imagine how I worried about you when I was told about the terrible accident. 

First I read the poem to myself and then ________ to the class.

The charity sale our school organizes every year has taught us much. _______ we would never have learned it in class.

He passed through a difficult period _____ after his marriage broke down.